RFR: Add start on a section about logging [v2]

[Ludvig Janiuk]

On Mon, 20 Dec 2021 09:24:20 GMT, Ludvig Janiuk <duke at openjdk.java.net> wrote:

>> It's hard to find information on how one should write logging code in Hotspot. This PR is only a first attempt at pointing the reader in the right direction, but a lot could be added in the future:
>>  * In which contexts can one not use unified logging?
>>  * How much should one log?
>>  * What other logging strategies are there?
>
> Ludvig Janiuk has updated the pull request incrementally with one additional commit since the last revision:
> 
>   cleanup

The fact is that there isn't a hotspot specific developer guide as of now. What's important to me is getting stuff like this documented *some place* a new member will find it. It's outrageous to come aboard as a new JVM developer, and have access to no documented answers to such basic necessities as logging, and just be expected to figure it out from hearsay. 

So could we just get it into the documentation-base as a first step, and leave discussions about perfect locations as step 2?

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PR: https://git.openjdk.java.net/guide/pull/70